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Biomedical subjects

Z Moldoveanu

Publications and source records attributed to Z Moldoveanu.

82 records · Page 5Linked to original sources
PubMed1985

Activity of rheumatoid factors of different molecular sizes: comparison of autologous monomeric and polymeric monoclonal IgA rheumatoid factors.

Differences in rheumatoid factor (RF) activity among the molecular species of IgA were investigated with the use of monomeric and polymeric monoclonal IgA RF paraprotein from the serum of a patient (PS) with idiopathic hyperviscosity syndrome. After fractionation by gel chromatography in acidic buffer, RF activity as determined by latex fixation and solid-phase radioimmunoassay (RIA) specific for IgA RF was confined to the high m.w. (greater than 7S) fractions. However, after adsorption into polystyrene wells, fractions containing monomeric (7S) IgA, as well as those containing polymeric IgA, bound 125I-labeled heat-aggregated human IgG. These observations were confirmed after further purification of the IgA fractions by passage through a protein A-Sepharose CL-4B column followed by precipitation of the IgA proteins with ammonium sulfate at 50% saturation. After "cross-linkage" by a hybridoma anti-human alpha-chain antibody, the activity of the monomeric IgA preparation in the IgA RF RIA approached that of the polymeric IgA preparation. Gel filtration studies verified that this activity was not due to contamination by polymeric IgA RF. Further, classic RF specificity was confirmed for both the monomeric and polymeric IgA RF by reaction with human Fc-coated but not Fab-coated wells. A control monomeric IgA myeloma protein and normal serum IgA did not react in the RF RIA when analyzed in the presence or absence of the hybridoma anti-alpha-chain antibody. Moreover, the activity of the polymeric IgA RF preparation from patient PS in the RIA was minimally influenced by the hybridoma antibody. These results indicate that IgA RF can coexist in both polymeric and monomeric forms, demonstrate that monomeric IgA RF may escape detection by previously described RIA techniques, and suggest an approach for its detection.

Animals↗
PubMed1984

Cellular origins of human polymeric and monomeric IgA: intracellular and secreted forms of IgA.

Intracellular and secreted IgA from pokeweed mitogen (PWM)-stimulated normal peripheral blood lymphocytes, from 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated peripheral blood lymphocytes of a patient with chronic lymphocytic leukemia (CLL), or from an IgA-producing human Epstein Barr virus (EBV)-transformed lymphoblastoid cell line were analyzed by molecular-sieve chromatography, electrophoresis in sodium dodecyl sulfate, and sucrose density ultracentrifugation. Fluorochrome-labeled anti-human IgA and secretory component (SC) were used as probes for the detection of polymeric IgA in individual cells. These methods demonstrated that the majority of intracellular IgA occurred in monomeric form, even when the predominant form of secreted IgA was polymeric. Sequential analyses of the IgA secreted by PWM-stimulated normal peripheral blood lymphocytes revealed that the proportion of polymeric IgA increased with the time of culture and that polymers represented the prevalent form of secreted IgA from the fifth day of culture. Although approximately one-half of TPA-stimulated CLL cells bound fluorochrome-labeled SC, only trace amounts of extracellular and intracellular polymeric IgA were detected in both culture supernatants and lysates. Culture supernatants of an IgA-secreting EBV-transformed cell line contained predominantly polymeric IgA. However, intracellular IgA was largely represented by monomers. The predominance of intracellular monomers in polymeric IgA-secreting cells suggested that the pathway of the assembly of human IgA molecules is analogous to that described for mouse IgA synthesis.

Autoradiography↗
PubMed1983

Ultrastructural studies of human lymphoid cells. mu and J chain expression as a function of B cell differentiation.

J chain expression was examined as a function of the stage in differentiation along the B cell axis in humans. Intracellular distribution of J and mu chains in leukemic HLA-DR+ null and pre-B cells, and in normal B cells stimulated with pokeweed mitogen (PWM) was determined by immunoelectron microscopy and radioimmunoassay (RIA). J chain was detected in leukemic null and pre-B cells on free and membrane-bound ribosomes in the cytoplasm, or on perinuclear cisternae. Mu chain was found on free ribosomes and ribosomal clusters in leukemic pre-B cells but was absent in the leukemic null cells. In pre-B cell lines, mu chain was seen within rough endoplasmic reticulum (RER) and the Golgi apparatus whereas J chain was not detected in these organelles. However, both mu and J chain were detected in RER and the Golgi apparatus of immature and mature plasma cells induced by PWM stimulation of normal peripheral blood lymphocytes. Low levels of J chain were also detected by RIA in lysates of leukemic null and pre-B cells. Most of the intracellular J chain became detectable after reduction and alkylation of cell lysates, and free J chain was not found in the culture supernatants. The amount of intracellular and secreted immunoglobulin-bound J chain increased dramatically after PWM stimulation of peripheral blood lymphocytes. The majority of J chain-positive cells seen over an 8 d culture interval were lymphocytes and lymphoblasts, while mu chain was found primarily in plasma cells. These results suggest that J chain expression precedes mu chain synthesis during B cell differentiation and that a combination of the two chains for secretion is not initiated until the onset of plasma cells maturation.

B-Lymphocytes↗
PubMed1983

Biosynthesis of J-chain in human lymphoid cells producing immunoglobulins of various isotypes.

The relationship between synthesis, secretion, and subcellular localization of J-chain, IgM, IgA, and IgG was investigated in cultures of PWM-stimulated human PBL and in lymphoblastoid cell lines. Cells were examined for surface, cytoplasmic, and secreted immunoglobulins (Igs) and J-chain by immunofluorescence and radioimmunoassay (RIA). By these techniques, J-chain was detected in cells that produce polymeric or monomeric Igs. In PWM-stimulated PBL the synthesis of J-chain paralleled the production of Igs. In both PWM-stimulated (for 2 days) and unstimulated PBL, equal proportions of free and disulfide-linked J-chain were found. Increased amounts of intracellular J-chain were produced at later stages in PWM-stimulated PBL and J-chain occurred mostly in a free form. In tissue culture fluids, J-chain was not secreted in a free form but was always disulfide-linked to polymeric Igs. In lymphoblastoid cell lines, J-chain was present in a disulfide-linked form in IgM and IGA producers, but in IgG cells and in an IgM cell line (DAUDI) that did not secrete IgM but expressed it on the cell membrane, intracellular J-chain was present in free form. Although various proportions of polymeric and monomeric IgA were seen in culture fluids from IgA-secreting cell lines, intracellular IgA occurred mostly in a monomeric form. Further studies revealed that the ability to produce polymers was not equally distributed among all cells and might vary according to their content of J-chain and stage of maturation. Subcellular fractionation and subsequent analyses for J-chain and Ig in PWM-stimulated PBL and in IgM or IgG-producing cell lines revealed that these proteins were associated with fractions that contained ribosomes, cell sap, and low molecular weight RNA. In lysates of IgG and J-chain producing cells grown in the presence of 3H-labeled amino acids, intracellular J-chain was not disulfide-linked to IgG.

Cell Line↗
PubMed1982

Human milk peroxidase is derived from milk leukocytes.

Peroxidase enzymes present in human colostrum, saliva, polymorphonuclear leukocytes, and bovine milk were compared with respect to their molecular exclusion chromatographic behavior and immunological cross-reactivity. Human milk peroxidase gave an elution profile similar to myeloperoxidase derived from blood polymorphonuclear leukocytes. Human salivary peroxidase reacted with an antibody directed against bovine lactoperoxidase, but with the same antibody preparation no reaction was detected either with human milk peroxidase or leukocyte myeloperoxidase. We conclude that the peroxidase enzyme in human milk is different from the human salivary and the bovine enzymes and is probably derived from milk leukocytes.

Colostrum↗
PubMed1982

Interaction of specific and innate factors of immunity: IgA enhances the antimicrobial effect of the lactoperoxidase system against Streptococcus mutans.

The antimicrobial effect of the lactoperoxidase (LPO) system (enzyme with the thiocyanate ion and hydrogen peroxide) on Streptococcus mutans NCTC 10449 (serotype c) was significantly enhanced when the system was combined with secretory IgA. Similar enhancement was observed with LPO-myeloma IgA1 or IgA2 combinations. This enhancement of the antimicrobial efficiency was not dependent on the presence of specific antibodies to S. mutans in the IgA preparation, but seemed to require binding between LPO and immunoglobulin. However, neither human polyclonal nor myeloma IgG or IgM nor rabbit IgG enhanced the antibacterial activity of the LPO system. None of the immunoglobulins, when added alone, produced antimicrobial effects. LPO was shown to bind to colostral secretory IgA, myeloma IgA1, IgA2, and to a lesser degree to monoclonal and polyclonal IgG and monoclonal IgM. This binding had a stabilizing effect on the enzyme activity. Our results suggest that IgA significantly enhances the antibacterial efficiency of one of the innate immune factors--the LPO system.

Animals↗
PubMedDate not supplied

Induction of specific immune responses in the genital tract of women after oral or rectal immunization and rectal boosting with Salmonella typhi Ty 21a vaccine.

The purpose of this study was to determine the efficacy of intestinal tract immunization in the induction of specific antibodies in human female genital tract secretions. Live attenuated typhoid vaccine Ty 21a was administered to three groups of healthy female volunteers, who were not using hormonal contraceptives. Group 1 included 15 women vaccinated orally. Group 2 included seven of the same women, who were vaccinated rectally 6 months later. Group 3 included 11 volunteers, who were vaccinated rectally. Salmonella-specific antibodies of IgG and IgA were measured in vaginal lavage and cervical mucus after oral or rectal primary vaccination. Salmonella-specific antibodies measured 1 month after rectal booster vaccination demonstrated significant increases in vaginal fluids and cervical mucus and were dominated by IgA. These results indicate that specific antibodies in the human female genital tract induced by primary vaccination can be enhanced by subsequent rectal administration of vaccines.

Administration, Oral↗
PubMedDate not supplied

The role of the liver in catabolism of mouse and human IgA.

The fate of intravascular IgA which is produced in large quantities in humans and many animal species was investigated in vivo and in vitro with emphasis on the monomeric form of IgA. The site(s) of the catabolism of intravenously injected mouse monomeric IgA labeled with a residualizing tracer (dilactitol - 125I tyramine) was studied in mice. The greatest in vivo uptake of monomeric IgA was observed in the liver. In contrast to identically labeled IgG, liver accounted for more internal catabolism of monomeric IgA than all other tissues (spleen, muscle, skin, and kidney) combined. Although both parenchymal and nonparenchymal liver cells internalized monomeric IgA, hepatocytes were far more active. The uptake of monomeric IgA was primarily mediated by the asialoglycoprotein receptor. In humans, the particulate fraction of liver homogenates and a human hepatoma cell line (Hep G2) bound human IgA proteins of various molecular forms. Inhibition of the binding by desialylated glycoproteins, requirement for the presence of calcium, and the molecular properties of the IgA-binding protein from the plasma membrane of Hep G2 cells indicated that the binding was primarily mediated by the asialoglycoprotein receptor. IgA proteins bound by Hep/G2 cells were internalized and catabolized to low molecular weight fragments.

Animals↗
PubMedDate not supplied

Cellular analysis of functional mononuclear cells from chronically inflamed gingival tissue.

Functional mononuclear cells from chronically inflamed gingiva of different stages of adult periodontitis (AP) were isolated by using a novel enzymatic dissociation method and extensively characterized at the single cell level. Fresh tissues obtained following surgery were cut into 1-2 mm3 pieces, washed free of residual blood cells and dissociated with the neutral protease enzyme Dispase. Mononuclear cells were then obtained by separation on a mini-Ficoll-Hypaque gradient. This procedure yields an average of 2 x 10(6) cells/400 mg of tissue. The viability of unfractionated cells immediately after enzymatic dissociation was greater than 94%, and after Ficoll-Hypaque gradient separation this was greater than 99%. The relative percentages of lymphocytes, plasma cells, monocytes (MN)/macrophages (M phi) and granulocytes were determined on cytospin preparations by Wright's-Giemsa staining. Cell differential analysis showed that lymphocytes and MN/M phi predominated at all stages of disease, while the frequency of plasma cells increased with the severity of disease. Numbers of plasma cells specific for IgG, IgA, or IgM were determined by immunofluorescence using fluoresceinated anti-heavy chain specific antibodies. The majority of Ig-containing cells were of the IgG isotype, followed by significant numbers of IgA and few IgM-positive cells. IgG, IgA, and IgM secreting cells were also determined by the ELISPOT assay. Total numbers of spot forming cells (SFC) were measured in both the moderate and advanced stages of disease, and the major SFC isotype was IgG followed by IgA; essentially no IgM SFC were detected. Furthermore, higher numbers of IgG and IgA SFC were noted in the advanced stage when compared with the moderate stage of disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗